Year 8 CCEA Biology: Formula & Theorem Quick Reference Handbook | CCEA 八年级生物：公式定理速查手册

📚 Year 8 CCEA Biology: Formula & Theorem Quick Reference Handbook | CCEA 八年级生物：公式定理速查手册

This handbook gathers every essential equation, formula, and theorem you need for Year 8 CCEA Biology. Whether you are calculating magnification, balancing photosynthesis, or recalling enzyme conditions, this revision tool puts the key facts at your fingertips.

本手册汇集了 CCEA 八年级生物必需掌握的所有重要方程、公式和定理。无论你是在计算放大倍数、配平光合作用方程，还是回忆酶的作用条件，这本复习工具都能让你快速找到关键知识点。

1. Photosynthesis Word Equation | 光合作用文字方程

Photosynthesis is the process by which green plants make their own food using light energy.

光合作用是绿色植物利用光能制造自身养料的过程。

The word equation summarises the reactants and products:

文字方程概括了反应物和生成物：

Carbon dioxide + Water → Glucose + Oxygen

二氧化碳 + 水 → 葡萄糖 + 氧气

• Light energy is absorbed by chlorophyll in chloroplasts to drive the reaction.

  光能被叶绿体中的叶绿素吸收，驱动反应进行。

• Glucose is stored as starch temporarily; some is used for respiration.

  葡萄糖暂时以淀粉形式储存；一部分用于呼吸作用。

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2. Aerobic Respiration Word Equation | 有氧呼吸文字方程

Respiration releases energy from glucose in all living cells.

呼吸作用在所有活细胞中分解葡萄糖释放能量。

Aerobic respiration requires oxygen and produces carbon dioxide and water as waste.

有氧呼吸需要氧气，并产生二氧化碳和水作为废物。

Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP)

葡萄糖 + 氧气 → 二氧化碳 + 水 + 能量（ATP）

• This takes place in mitochondria.

  这发生在线粒体中。

• Energy is used for movement, growth, and keeping warm.

  能量用于运动、生长和维持体温。

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3. Anaerobic Respiration in Humans (Word Equation) | 人体无氧呼吸（文字方程）

When oxygen is limited, muscle cells switch to anaerobic respiration.

当氧气不足时，肌肉细胞转为无氧呼吸。

It produces lactic acid and much less energy.

它产生乳酸和少得多的能量。

Glucose → Lactic acid + Energy

葡萄糖 → 乳酸 + 能量

• Lactic acid builds up and causes muscle fatigue and cramps.

  乳酸堆积会引起肌肉疲劳和抽筋。

• Oxygen debt is the extra oxygen needed after exercise to break down the lactic acid.

  氧债是运动后分解乳酸所需的额外氧气。

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4. Anaerobic Respiration in Yeast (Fermentation) | 酵母菌的无氧呼吸（发酵）

Yeast and some microorganisms produce ethanol and carbon dioxide instead of lactic acid.

酵母和某些微生物产生乙醇和二氧化碳，而非乳酸。

Glucose → Ethanol + Carbon dioxide + Energy

葡萄糖 → 乙醇 + 二氧化碳 + 能量

• This is used in baking (CO₂ makes bread rise) and brewing (ethanol).

  这用于烘焙（CO₂ 使面包发酵）和酿酒（乙醇）。

• Yeast cells can switch to aerobic respiration when oxygen is present.

  有氧气时，酵母细胞可切换为有氧呼吸。

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5. Microscope Magnification Formula | 显微镜放大倍数公式

Calculating total magnification is a core skill in CCEA Biology.

计算总放大倍数是 CCEA 生物的核心技能。

Total Magnification = Eyepiece lens magnification × Objective lens magnification

总放大倍数 = 目镜放大倍数 × 物镜放大倍数

• Common eyepiece: ×10; objectives: ×4, ×10, ×40.

  常见目镜：×10；物镜：×4、×10、×40。

• Example: 10 × 40 = ×400 total magnification.

  例：10 × 40 = ×400 总放大倍数。

• To calculate real cell size, use:

  计算实际细胞尺寸，使用：

Real size = Image size ÷ Magnification

实际大小 = 图像大小 ÷ 放大倍数

• Teach yourself to convert units: 1 mm = 1000 µm.

  学会单位换算：1 毫米 = 1000 微米。

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6. Enzyme Activity – Lock and Key Model | 酶活性 – 锁钥模型

Enzymes are biological catalysts that speed up reactions without being used up.

酶是生物催化剂，能加速反应而本身不被消耗。

The ‘lock and key’ theorem states:

“锁钥模型”定理指出：

• Every enzyme has an active site shaped specifically for its substrate (key).

  每种酶都有一个特定形状的活性位点，只与底物（钥匙）匹配。

• Substrate fits into the active site, forming an enzyme-substrate complex.

  底物嵌入活性位点，形成酶-底物复合物。

• Reaction occurs, products are released, enzyme remains unchanged.

  反应发生，产物释放，酶保持不变。

Enzymes are denatured by high temperatures or extreme pH, changing the shape of the active site permanently.

高温或极端 pH 会使酶变性，永久改变活性位点的形状。

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7. Optimum Conditions for Enzymes | 酶的最适条件

Each enzyme works best at a specific temperature and pH – this is its optimum.

每种酶在特定的温度和 pH 下工作效率最高——这就是其最适条件。

Enzyme	Optimum Temperature	Optimum pH
Human amylase	37 °C (body temp)	pH 7 (neutral)
Pepsin (stomach)	37 °C	pH 2 (acidic)
Plant enzymes (e.g., catalase)	~20-25 °C	pH 7-8

Understanding these conditions helps explain why high fever or changes in pH can stop metabolic reactions.

理解这些条件有助于解释为什么高烧或 pH 改变会停止代谢反应。

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8. Diffusion Theorem | 扩散定理

Diffusion is the net movement of particles from a region of high concentration to a region of low concentration, down a concentration gradient.

扩散是粒子从高浓度区域向低浓度区域的净运动，沿浓度梯度进行。

• It is a passive process — no energy is needed.

  这是被动过程——不需要能量。

• Rate of diffusion increases with higher temperature, steeper gradient, and larger surface area.

  温度越高、浓度梯度越陡、表面积越大，扩散速率越快。

• Examples: oxygen entering blood in lungs, carbon dioxide leaving, nutrients absorbed by cells.

  例子：氧气进入肺部血液，二氧化碳排出，营养物质被细胞吸收。

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9. Osmosis – A Special Case of Diffusion | 渗透——扩散的一种特殊情况

Osmosis is the diffusion of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution.

渗透是水分子通过部分透性膜从稀溶液向较浓溶液扩散的过程。

• No energy is required.

  不需要能量。

• Plant cells in pure water become turgid (firm) because water enters by osmosis.

  植物细胞在纯水中因水分进入而膨胀（变得坚挺）。

• In a concentrated sugar/salt solution, plant cells lose water and become flaccid (plasmolysis).

  在浓糖/盐溶液中，植物细胞失水变得萎蔫（质壁分离）。

• Animal cells can burst (lysis) in pure water if too much water enters — they lack a cell wall.

  动物细胞在纯水中如果进水过多会破裂（溶胞）——它们缺乏细胞壁。

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10. Food Chain Energy Transfer and the 10% Rule | 食物链能量传递与百分之十定律

In any food chain, energy is transferred from one trophic level to the next, but most is lost.

在任何食物链中，能量从一个营养级传递到下一个，但大部分能量会损失。

Energy available at next level ≈ 10% of energy at previous level

下一营养级可用的能量 ≈ 上一营养级能量的 10%

• Losses occur through movement, heat, uneaten parts, and excretion.

  损失途径包括运动、散热、未被食用的部分以及排泄。

• About 90% of energy is lost between levels, which explains why food chains rarely have more than 4-5 links.

  营养级间大约 90% 能量损失，这解释了为什么食物链很少有超过 4-5 个环节。

• Pyramids of energy or biomass represent this transfer.

  能量金字塔或生物量金字塔可表示这种传递。

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11. Photosynthesis Limiting Factors Summary | 光合作用限制因素总结

The rate of photosynthesis is limited by the factor that is in shortest supply.

光合作用速率受供应最少的因素限制。

Factor	Effect
Light intensity	Up to a point, more light increases rate. Beyond saturation, no effect.
Carbon dioxide concentration	Rising CO₂ boosts rate until another factor becomes limiting.
Temperature	Enzymes work faster up to optimum; too high causes denaturation.

The theorem: the factor that is lowest relative to the plant’s need will be the limiting factor at any given moment.

定理：相对于植物的需求而言，数值最低的那个因素在特定时刻就是限制因素。

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12. Key Biological Units and Symbols Quick Guide | 关键生物单位与符号速查

Memorise these frequently used units and symbols to avoid mistakes in calculations and graphs.

熟记这些常用单位和符号，可避免计算和图表中的错误。

• Length: 1 centimetre (cm) = 10 millimetres (mm); 1 mm = 1000 micrometres (µm)

  长度：1 厘米 (cm) = 10 毫米 (mm)；1 毫米 = 1000 微米 (µm)

• Temperature: °C (degrees Celsius)

  温度：°C（摄氏度）

• Energy: kilojoules (kJ)

  能量：千焦 (kJ)

• Magnification: × (times)

  放大倍数：×（倍）

• Biomass: grams per square metre (g/m²)

  生物量：克每平方米 (g/m²)

Using correct units turns a one-mark guess into a confident, full-mark answer.

使用正确的单位能将碰运气的答案变成有信心拿满分的解答。

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